Argatroban Monohydrate

Argatroban is highly selective for thrombin and has little or no effect on related serine proteases (trypsin, factor Xa, plasmin, and kallikrein). Argatroban is effective against free, fibrin-bound and clot-bound thrombin with comparable half-maximal inhibitory concentrations (IC50), and argatroban is also effective in inhibiting platelet aggregation and thromboxane generation in the presence of both free and clot-bound thrombin^[1]. Argatroban binds thrombin and inhibits its activity without the requirement of coenzymes, unlike antithrombin III or heparin cofactor II. Argatroban decreases bone metastasis of B16 mouse melanoma cells by inactivating thrombin activity. Moreover, argatroban has potential to inhibit PAR-2 activation by interfering with the thrombogenic cycle. It does not have toxic effect for tumor cells^[2].

Tissue factor (TF) activity was measured as factor X (FX) activation by the factor VIIa (FVIIa)/TF complex on MDA-231 cells. MDA-231 cells were starved in serum-free medium for 24 h, following incubation with FBS for 24 h (24-well plate, 2.0 × 10⁵ cells/well). After starvation, MDA-231 cells were treated with thrombin (0.1-10 U/ml) in presence or absence of argatroban (0.1-1 μM) for 4 h.

Within a clinically relevant dose range (from 1–3 μg/kg/min in prevention or treatment of thrombotic events in HIT to up to 25 μg/kg/min in PCI in HIT patients), argatroban exhibits linear pharmacokinetic behavior, and steady state levels are attained within 1 hour after the start of an infusion. The elimination half-life of argatroban in healthy subjects is about 45 minutes, with a corresponding decline in its anticoagulant effects which reach their pretreatment level within 2–4 hours after cessation of an infusion. Argatroban lacks major drug–drug interactions with CYP3A4/5 inhibitors such as erythromycin or with acetaminophen, warfarin, and digoxin. However, in patients with hepatic impairment, area under the concentration versus time curve (AUC), maximum concentration, and half-life of argatroban were increased approximately 2- to 3-fold, and clearance was one-fourth that of healthy volunteers. The increase in plasma concentrations in these patients coincided with increased pharmacodynamic effects^[1].